We propose to conduct this International Research Collaboration on Drug Addiction (in response to PA-07-275) to address the growing public health threat from substance abuse in Egypt, where resources for healthcare in general, and for addiction control and research in particular (including both tobacco and other drugs of addiction), are severely lacking. Using a participatory, mixed methods research design, we will conduct both quantitative and qualitative surveys. We will recruit nationally representative samples of youths 10-18 years old, including those attending school (N=10,800) and those not attending school (N=540), from the three regions of Egypt (Upper Egypt, Lower Egypt, and Cairo). We will also conduct in-depth qualitative interviews and focus groups with youth in this same age range, to discern further details of their tobacco and other drug use behaviors, and of the correlates of their use, including the risks and protective factors. The specific aims of the study are as follows. Aim 1: To conduct an in-depth qualitative study of the tobacco and other drug use behaviors of youths and of the correlates of use, including the situational and environmental protective and risk factors. The results of this aim will shed light on the etiologies of drug use among Egyptian youth, and support the design of the quantitative survey instrument. Aim 2: To conduct a large-scale Prevalence Survey to assess substance use and abuse behaviors in youths and to discern correlates of use; respondents will include both males and females nationally representative of urban and rural areas in the three regions of Egypt (Upper Egypt, Lower Egypt, and Cairo). We will survey both in-school and out-of-school youth populations.